We are using X-ray absorption spectroscopy (EXAFS and XANES) to study the metal site in a manganese-enzyme, prolidase. Although manganese-enzymes are a class of proteins with important biological functions, the coordination of the metal and the reasons why manganese(II) is required for the activity of the enzymes have hitherto received little attention. Prolidase is of particular interest because defects in the enzyme are identified with specific clinical symptoms of a congenital molecular disease. The planned X-ray absorption measurements on prolidase and prolidase-inhibitor complexes have been preceeded by a detailed study of model complexes in order to benchmark the EXAFS parameters as well as new software to be used in the structure-fitting calculations.